1. Field of the Invention
The present invention relates to an antenna, and more particularly, to a new antenna structure constructed by combining two (or more) identical antennas being symmetrically disposed in the left and right sides of a signal feeding element (e.g., arranged in an array), so as to achieve a goal of simultaneously receiving a LHCP signal and a RHCP signal.
2. Description of the Prior Art
Recently, requirements for satellite receiving systems have increased year by year due to satellite communication services having characteristics of wide bandwidth, data broadcasting, and being borderless. However, the resources for satellite bandwidth are finite. Thus, transmission manners such as linear polarization transmission and circular polarization transmission are developed to make better use of the satellite bandwidth. The linear polarization transmission consists of vertical linear polarization (VLP) and horizontal linear polarization (HLP), wherein the magnitude of its electric field varies over time but the direction of the electric field remains the same. The circular polarization transmission consists of right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP), wherein the magnitude of its electric field does not vary over time, but the direction of the electric field does.
At present, patch antennas or ceramic chip antennas made up of ceramic materials are usually used for receiving the circular polarization signals in the satellite receiving systems. Since the ceramic materials have larger dielectric constants and smaller dielectric losses, they are suitable for high-frequency communications. However, regardless of patch antennas or ceramic chip antennas, the products must have the corresponding thickness due to the thicknesses of such antennas are thicker (about 5˜10 mm). In addition, a single antenna of the present satellite receiving systems can only be used for receiving the RHCP signal or the LHCP signal. Hence, two antennas are required to be able to simultaneously receive the RHCP signal or the LHCP signal. That is, the radiation efficiency and the directionality of magnetic field of such antennas are obviously insufficient.